miller 251with 75/25

by Dean

What formula do i use to set the voltage and also the wire feed speed, i am learning the machine but i don't know how to adjust when i have to weld vertical, can u help? I am mostly welding. 3/8", 1/2", some 5/8", track hoe bucket rebuilds and miscellaneous.


One method to find good mig welding settings using a millermatic 251 is to use the chart on the inside of the panel door.

In my opinion, these settings are across the board about 10 % higher on wire speed than what I prefer....but its a good starting point.

for vertical welds, I find that choosing about 2 thicknesses less than what I am welding gives a pretty good setting ( minus the 10% )

The miller weld calculator seems to be about the same as the charts they use for the millermatic welders..

is a good resource. but it is intended to be used for single pass horizontal fillet welds and the settings are pretty hot for anything but flat , horizontal, or downhill.

so what you can do for vertical uphill settings is select the thickness for about half of what you are welding and then use the weld calculator

for example, half of 3/8" is 3/16" so the settings for 3/16" using 75/25 with .035" bare wire are 18-19 volts and 320-340 ipm...that should work pretty well for vertical uphill on 3/8"...give or take. you may need 19-20 volts but its a good start.

once you get a good match of voltage and wire speed,, if its too hot or cold , just increase or decrease both voltage and wire to suit the heat you need.

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